This invention relates to the protection of software, software transmission, data transmission, etc., and more particularly to the protection of distributed data from unauthorized use in contrast to the prevention of copying of programs or protection of programs by execution control means.
Generally, the primary purpose of software protection is to prevent the duplication and use of a program without the purchase or payment of a fee. A number of solutions have been advanced to deal with such problems, e.g., U.S. Pat. Nos. 4,562,306; 4,932,054 and 5,081,676. All require additional hardware which probably would not be economically viable in a mass mailing type distribution of software.
A different problem is encountered when some type of distribution is used to market the program in contrast to direct point of sale marketing. In one such an arrangement the program may be mass produced, e.g., records in the form of CD ROMs, and sent out by a mailing. Such CD ROMs can combine a multiplicity of independent programs or related programs which may be selected individually or in different combinations. The idea is then to restrict the possibility to use a particular program only to those willing to pay for that program and to prevent others who have not obtained authorization from such use. For example, if the user must call in to get a key which is then used to run a particular distributed program and this key is the same for all copies of this program, there is nothing to prevent the caller from simply giving the key to a third party who then may access the program without paying for such use.